This invention relates to the preparation of a carboxylic acid from the corresponding alkali metal or ammonium carboxylate in an aqueous solution. In particular, this invention relates to the use of liquid ion exchange agents for the conversion of salts of carboxylic acids into the corresponding carboxylic acids.
Among the various methods previously used for the recovery of carboxylic acids from their salts, the most common has been acidification with an aqueous solution of a mineral acid. This method has not been entirely satisfactory for the recovery of water-soluble carboxylic acids or aminopolycarboxylic acids, which are chelating agents. The water-soluble carboxylic acids are difficult to separate from the salts of mineral acids.
The practice of this invention is useful to produce in high yield carboxylic acids free of contaminant by-product salts produced in the conventional acidification reactions.